<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>example1_11.html</title>
<script type="text/javascript">
	var firstNumber = "I am a String";
	var secondNumber = 300;
	var thirdNumber = firstNumber + secondNumber;
	alert(thirdNumber);
	alert("firstNumber的值类型：" + typeof(firstNumber));
	alert("secondNumber的值类型：" + typeof(secondNumber));
	alert("thirdNumber的值类型：" + typeof(thirdNumber));
</script>
</head>
<body>
</body>
</html>
